Soft material adhesion characterization for in vivo locomotion of robotic capsule endoscopes: Experimental and modeling results

Madalyn D Kern; Joan Ortega Alcaide; Mark E Rentschler

doi:10.1016/j.jmbbm.2014.07.032

Soft material adhesion characterization for in vivo locomotion of robotic capsule endoscopes: Experimental and modeling results

J Mech Behav Biomed Mater. 2014 Nov:39:257-69. doi: 10.1016/j.jmbbm.2014.07.032. Epub 2014 Aug 7.

Authors

Madalyn D Kern¹, Joan Ortega Alcaide², Mark E Rentschler³

Affiliations

¹ University of Colorado at Boulder, 427 UCB, 1111 Engineering Dr., Boulder, CO 80309-0427, USA. Electronic address: madalyn.kern@colorado.edu.
² University of Colorado at Boulder, 427 UCB, 1111 Engineering Dr., Boulder, CO 80309-0427, USA; Polytechnic University of Catalonia, Diagonal Avenue, 647, 08034 Barcelona, Spain. Electronic address: joan.ortegaalcaide@colorado.edu.
³ University of Colorado at Boulder, 427 UCB, 1111 Engineering Dr., Boulder, CO 80309-0427, USA. Electronic address: mark.rentschler@colorado.edu.

PMID: 25151447
DOI: 10.1016/j.jmbbm.2014.07.032

Abstract

The objective of this work is to validate an experimental method and nondimensional model for characterizing the normal adhesive response between a polyvinyl chloride based synthetic biological tissue substrate and a flat, cylindrical probe with a smooth polydimethylsiloxane (PDMS) surface. The adhesion response is a critical mobility design parameter of a Robotic Capsule Endoscope (RCE) using PDMS treads to provide mobility to travel through the gastrointestinal tract for diagnostic purposes. Three RCE design characteristics were chosen as input parameters for the normal adhesion testing: pre-load, dwell time and separation rate. These parameters relate to the RCE׳s cross sectional dimension, tread length, and tread speed, respectively. An inscribed central composite design (CCD) prescribed 34 different parameter configurations to be tested. The experimental adhesion response curves were nondimensionalized by the maximum stress and total displacement values for each test configuration and a mean nondimensional curve was defined with a maximum relative error of 5.6%. A mathematical model describing the adhesion behavior as a function of the maximum stress and total displacement was developed and verified. A nonlinear regression analysis was done on the maximum stress and total displacement parameters and equations were defined as a function of the RCE design parameters. The nondimensional adhesion model is able to predict the adhesion curve response of any test configuration with a mean R(2) value of 0.995. Eight additional CCD studies were performed to obtain a qualitative understanding of the impact of tread contact area and synthetic material substrate stiffness on the adhesion response. These results suggest that the nondimensionalization technique for analyzing the adhesion data is sufficient for all values of probe radius and substrate stiffness within the bounds tested. This method can now be used for RCE tread design optimization given a set of environmental conditions for device operation.

Keywords: In vivo; Normal adhesion; Robotic locomotion; Soft material.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biocompatible Materials / chemistry
Capsule Endoscopes*
Cell Adhesion
Dimethylpolysiloxanes / chemistry
Endoscopy / methods*
Equipment Design
Humans
Intestines / pathology
Linear Models
Materials Testing
Regression Analysis
Robotics*
Stress, Mechanical
Surface Properties

Substances

Biocompatible Materials
Dimethylpolysiloxanes
baysilon